When conventional switches and routers receive input data, they must examine the contents of the input data stream to determine where to direct the data. In order to find the relevant switching and routing information within the stream of data, frames and cells in the data must be identified (i.e. “delineated”) and packets must be extracted from their digital “envelope” via a process known as “decapsulation.” Decapsulation is performed in conventional switches and routers by software that executes on a processor. Software directs the decapsulation to ensure that the decapsulation is performed properly.
The data must be re-encapsulated after it has been decapsulated so that it may be sent out of the switch or router in the digital envelope required by the outgoing link. In conventional routers the re-encapsulation is performed by software that executes on a processor.